Re: Configuring mount for NTFS partition at boot makes the system unbootable.

[William <willbilly@fedora.email>]

On Sun, 03 Mar 2024 16:15:56 -0800
Felix Lechner <felix.lechner@lease-up.com> wrote:

> Hi William,
> 
> It seems that help-guix was inadvertently left off of the recipients.
>  I hope you don't mind that I copied the mailing list on your
> response.
> 
> On Sun, Mar 03 2024, William wrote:
> 
> > Hello.
> >
> > Thanks for the input, this certainly helped me diagnose the issue.
> >
> > I set some options so Guix keeps booting if mounting the filesystem
> > fails, now I can boot.
> >
> > I potentially figured out what the issue may be, the filesystem
> > entry is defined on /etc/fstab so I tried running "mount -a"
> > without root, and it printed this:
> >  
> >> Mount is denied because setuid and setgid root ntfs-3g is insecure
> >> with the external FUSE library. Either remove the setuid/setgid bit
> >> from the binary or rebuild NTFS-3G with integrated FUSE support and
> >> make it setuid root.
> >> Please see more information at
> >> https://github.com/tuxera/ntfs-3g/wiki/NTFS-3G-FAQ  
> >
> > It seems it's another issue with setuid/setgid. I think this could
> > be solved if ntfs-3g is compiled with integrated FUSE support, so
> > it doesn't require libfuse at all, then the declaration to load the
> > FUSE module wouldn't be needed either I suppose.  
> 
> I also use FUSE every day and believe it's compiled into our kernels
> (i.e. no module). Perhaps someone can help you find our kernel
> configurations.
> 
> The security concern may also be further explained here. [1]
> 
> > Maybe this should be reported as an issue on the Guix tracker?  
> 
> There is already a bug about it. [2] The filing is from 2021. There is
> no proposed solution.
> 
> I would write to the bug [3] and ask if there are workarounds. Please
> make sure to cc Abdelhakim, whose address you can find here. [4] (I
> also copied him on this message.) No one else will receive or read
> your message to the bug tracker.
> 
> Kind regards
> Felix
> 
> P.S. Sorry about the complexity of our bug reporting tools. Some work
> is being done to simplify them.
> 
> [1]
> https://unparalleled.eu/blog/2022/20220607-help-to-heap-suid-privilege-escalation/
> [2] https://issues.guix.gnu.org/46980 [3] 46980@debbugs.gnu.org
> [4] https://debbugs.gnu.org/46980

Hello again Felix.

As a matter of fact, I was testing this using the upstream "corrupted"
kernel from the nongnu channel. I just tried the same with Linux-libre
6.1.79, with the same behaviour, so I think the issue is not the FUSE
module not being loaded but rather ntfs-3g relying on the external FUSE
to mount partitions.

The only two possible workarounds I can see is either manually mounting
the partition on boot as sudo/superuser, or compile ntfs-3g modified
locally with the FUSE support enabled, and use the modified version
instead, but I've got no clue of how to do such thing on Guix, I'm
still trying to get the system configured exactly as I'd like to before
digging into something like that.

Meanwhile I'll file a reply as a reminder to that issue, maybe the
package mantainers can eventually patch ntfs-3g.

Thank you.